What Could Be Causing My Persistent Burning Feet Despite Treatment With Gabapentin And Vitamin B12?

Hello doctor... I have been feeling burning feet now for a month but no change..I visited hospital twice aget medication for the first visit but it did not help,for the second time they give me gabapentin and vitamin b12. Once I finish the dosage after 14days....a week after I started feeling the sem thing..... I took all the test like diabetes,hiv,high blood pressure,full blood count,,but all was fine... But now I don t know what could be the reason....???